Re: [PATCH 2/2] livepatch: Fix the bug if the function name is larger than KSYM_NAME_LEN-1

From: Josh Poimboeuf
Date: Mon Apr 13 2015 - 19:13:23 EST

On Sun, Apr 12, 2015 at 09:15:54PM +0800, Minfei Huang wrote:
> For now, the kallsyms will only store the first (KSYM_NAME_LEN-1). The
> kallsyms name is same for the function which first (KSYM_NAME_LEN-1) is
> same, but the rest is not.
> Then function will never be patched, although function name and address
> are provided both. The reason caused this bug is livepatch cannt
> recognize the function name.
> Now, livepatch will verify the function name with first (KSYM_NAME_LEN-1)
> and address, if provided. Once they are matched, we can confirm that the
> patched function is found.

>From scripts/kallsyms.c:

if (strlen(str) > KSYM_NAME_LEN) {
fprintf(stderr, "Symbol %s too long for kallsyms (%zu vs %d).\n"
"Please increase KSYM_NAME_LEN both in kernel and kallsyms.c\n",
str, strlen(str), KSYM_NAME_LEN);
return -1;

So I think such a long symbol name wouldn't be added to the kallsyms
database in the first place.

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